actually houses in my area are so big, with hot tubs electric cars requiring 50kw fast chargers etc its not hard to find a house sized with 400amps, throw in a detached garage you can easily get permit for another 300 watt for a garage shop.
Its false that they make you pay for the transformer all they need is a city permit and they put up the pole if needed.
power is not an issues. the issue is residential rates are bad for mining. Im my shop i have businesses rates , slowly moving my rigs there. I pay .04 plus deman rate in the garage. In my residence i pay 12 to 15. cents in summer no less than .11 in winter
Well, just because the main breaker says 400A doesn't mean you can actually draw 400A for more than a few seconds. Firstly, the NEC limits maximum continuous use of any circuit to 80% of the wiring or breaker rating, whatever is less (usually the breaker). Secondly, the distribution transformer (usually affectionately referred to as a "pig" if mounted on a utility pole) will likely be rated for 10kVA to 50kVA if pole-mounted, and 50kVA to 200kVA if pad-mounted, and each transformer will likely serve 1 - 6 houses so you really don't have nearly as much power available as you might think.
Our esteemed OP can probably provide a bit more detail on this seeing as he has had major electrical service work done, along with solar tie-ins, etc.